This invention generally relates to tape cassettes, and more particularly, to a novel structure for the tape reels of a tape cassette to improve operation of the tape cassette and avoid damage of the tape.
A conventional tape cassette tape reel structure is described in U.S. Pat. No. 4,560,117 (the '117 patent), issued to SHIMIZU, and shown in FIG. 1 herein. This figure illustrates top and bottom cassette halves 10, 12, respectively, molded of a clear synthetic resin, a tape guide 14, guide rollers 16 and guide pins 18 located at the front of the cassette half 12. The top and bottom cassette halves 10, 12, each include a pair of annular rings 20 and are connected via screws 22. A pair of tape reels 24 are mounted for centering and rotational support on the annular rings 20. The tape reels 24, which receive the tape 32 thereon, include a pair of planar, parallel and circular flanges 30. The flanges 30 are each stamped components made of metal, such as aluminum, and are attached to a synthetic resin hub 26 via a plurality of raised plastic fitting projections 40 with four circular resin washers 28 therebetween.
Metal is used to form these flanges because the required strength or structural integrity of the flange can be accomplished using a metal flange which is thinner than a comparable plastic flange. As a result, material costs and space useage can be minimized. However, when the flanges are stamped from metal, the edges are necessarily formed perpendicular to the flat, parallel tops and bottoms. In addition, the edges invariably develop burrs through the stamping process which abrade the edges of the tape travelling thereacross during operation. Further, during assembly and later handling, it is possible that one or both of the flanges could be permanently bent. Bending of the flanges occurs particularly when the related tape reel does not include any tape and the cassette halves are pinched in some manner. Once the flanges are bent, the edges of the travelling tape contact the edges of the bent flange or flanges, which also causes tape damage.
The hub 26 has an inner peripheral step 34 formed at a diameter slightly larger than the outside diameter of the corresponding annular ring 20. The ends of the annular rings 20 abut the hubs 26 only at the inner peripheral step 34, such that both sides of the tape reel 24 and the metal flanges 30 are separated from the cassette halves 10, 12, by a specific clearance. Spindles of a tape player recorder (not shown) are received by the center holes 36 formed in the hubs 26, and radial projections 38 extending into the center holes 36 engage the spindles to transfer torque from the rotating spindles to the tape reels 24 through the hub 26.
According to this conventional tape reel supporting structure, the only area of contact between the tape reels and the tape cassette is between the pair of inwardly extending annular rings of relatively small diameter formed on each plastic tape cassette half, and the corresponding inner peripheral steps formed on each plastic tape reel hub for centering purposes. Support of the tape reels in this manner causes the abutting plastic inner peripheral steps and the plastic annular rings to wear due to friction, which in turn generates unwanted noise and debris. In addition, supporting via a relatively small diameter permits skewing of the tape reels relative to each other within the tape cassette, leading to possible edge damage of the tape moving between the skewed tape reels.
From the foregoing, it can be seen that an improved tape reel for a tape cassette is desired which minimizes wear, maintains its intended position and prevents damage to the travelling tape.